﻿using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Furion.Application
{
    public class Helper
    {
        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="originalImagePath">源图路径（物理路径）</param>
        /// <param name="thumbnailPath">缩略图路径（物理路径）</param>
        /// <param name="width">缩略图宽度</param>
        /// <param name="height">缩略图高度</param>
        /// <param name="mode">生成缩略图的方式</param>    
        public static bool MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
        {
            bool f = false;
            if (System.OperatingSystem.IsWindows())
            {
                System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

                if (originalImage.Width > width)
                {
                    int towidth = width;
                    int toheight = height;

                    int x = 0;
                    int y = 0;
                    int ow = originalImage.Width;
                    int oh = originalImage.Height;

                    switch (mode)
                    {
                        case "HW"://指定高宽缩放（可能变形）                
                            break;
                        case "W"://指定宽，高按比例                    
                            toheight = originalImage.Height * width / originalImage.Width;
                            break;
                        case "H"://指定高，宽按比例
                            towidth = originalImage.Width * height / originalImage.Height;
                            break;
                        case "Cut"://指定高宽裁减（不变形）                
                            if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                            {
                                oh = originalImage.Height;
                                ow = originalImage.Height * towidth / toheight;
                                y = 0;
                                x = (originalImage.Width - ow) / 2;
                            }
                            else
                            {
                                ow = originalImage.Width;
                                oh = originalImage.Width * height / towidth;
                                x = 0;
                                y = (originalImage.Height - oh) / 2;
                            }
                            break;
                        default:
                            break;
                    }

                    //新建一个bmp图片
                    System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

                    //新建一个画板
                    Graphics g = System.Drawing.Graphics.FromImage(bitmap);

                    //设置高质量插值法
                    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

                    //设置高质量,低速度呈现平滑程度
                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

                    //清空画布并以透明背景色填充
                    g.Clear(System.Drawing.Color.White);

                    //在指定位置并且按指定大小绘制原图片的指定部分
                    g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
                        new System.Drawing.Rectangle(x, y, ow, oh),
                        GraphicsUnit.Pixel);

                    try
                    {
                        //以jpg格式保存缩略图
                        bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
                        f = true;
                    }
                    catch (System.Exception e)
                    {
                        f = false;
                    }
                    finally
                    {
                        originalImage.Dispose();
                        bitmap.Dispose();
                        g.Dispose();
                    }
                }
            }
            else
            {
                //System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);
                using (var originalImage = SixLabors.ImageSharp.Image.Load(originalImagePath))
                {
                    if (originalImage.Width > width)
                    {
                        int towidth = width;
                        int toheight = height;

                        int x = 0;
                        int y = 0;
                        int ow = originalImage.Width;
                        int oh = originalImage.Height;

                        switch (mode)
                        {
                            case "HW"://指定高宽缩放（可能变形）                
                                break;
                            case "W"://指定宽，高按比例                    
                                toheight = originalImage.Height * width / originalImage.Width;
                                break;
                            case "H"://指定高，宽按比例
                                towidth = originalImage.Width * height / originalImage.Height;
                                break;
                            case "Cut"://指定高宽裁减（不变形）                
                                if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                                {
                                    oh = originalImage.Height;
                                    ow = originalImage.Height * towidth / toheight;
                                    y = 0;
                                    x = (originalImage.Width - ow) / 2;
                                }
                                else
                                {
                                    ow = originalImage.Width;
                                    oh = originalImage.Width * height / towidth;
                                    x = 0;
                                    y = (originalImage.Height - oh) / 2;
                                }
                                break;
                            default:
                                break;
                        }


                        try
                        {
                            using var newImage = originalImage.Clone(imageProcessing =>
                            {
                                imageProcessing.AutoOrient();
                                imageProcessing.Resize(towidth, toheight);
                                imageProcessing.Crop(new SixLabors.ImageSharp.Rectangle(x: 0, y: 0, width: towidth, height: toheight));
                                //imageProcessing.Rotate(RotateMode.Rotate90);
                                //imageProcessing.Flip(FlipMode.Vertical);
                            });
                            newImage.SaveAsJpeg(thumbnailPath, new SixLabors.ImageSharp.Formats.Jpeg.JpegEncoder { Quality = 100 });
                            f = true;
                        }
                        catch (System.Exception e)
                        {
                            f = false;
                        }
                        finally
                        {
                            originalImage.Dispose();
                        }                        
                    }
                }                    
            }            
            return f;
        }
    }
}
